In an arc welding process, there is an initial start up phase or arc initiation phase where the wire feeder motor accelerates from a run in speed to a desired steady state wire feed speed. On some occasions the motor may start from a complete stop such that the run-in speed is zero. In accelerating to the desired wire feed speed, the motor speed ramps upward from the run in speed toward the desired wire feed speed. Typically the motor will briefly overshoot the desired wire feed speed. As a result, the arc, which is keyed to the desired wire feed speed, will often be overpowered as the motor ramps up or under powered when the motor overshoots the wire feed speed. The practical effect is that when the arc is overpowered, the arc creates spattering of the weld material. When underpowered relative to the wire feed speed, wire stubbing may occur. Both of these lead to imperfections in the appearance and potentially the quality of the weld during arc initiation. Once the welding system reaches steady state and is operating at the desired wire feed speed, coordination between the arc and the wire feed speed is generally well controlled, and the practical issues of spatter and stubbing seen during initiation are a much less likely to occur.
Relative to the steady state operation of the welding system, the arc initiation phase is short, and may last less than 14 milliseconds. This time period is provided as an example, and should not be considered limiting as it is expected that the length of the arc initiation phase may vary depending on the welding machine and application. Nevertheless, it is desirable to create a high quality weld with a consistent appearance as soon as possible. Ideally, the arc and wire feed motor will be synchronized during arc initiation to produce a flawless weld throughout the entire welding process.